In the manufacture of wet laid facial tissue, bathroom tissue, or paper towels it is necessary to crepe the dried fibrous web in order to impart to the web the desired feel characteristics, such as softness and bulk. The creping process involves adhering the web to a rotating creping cylinder, such as a Yankee dryer, and thereafter dislodging the adhered web with a doctor blade. The impact of the web against the doctor blade causes the web to buckle and ruptures some of the fiber-to-fiber bonds within the web. The severity of this creping action is dependent upon a number of factors, including the degree of adhesion between the web and the surface of the creping cylinder. Greater adhesion causes increased softness, although there generally is some loss of strength. In order to increase adhesion, a creping adhesive is generally sprayed onto the surface of the creping cylinder to augment any naturally occurring adhesion which the web may have due to its water content when applied to the creping cylinder. Water content will vary widely depending on the extent to which the web has been previously dried.
A wide variety of creping adhesives are known in the art, such as polyvinyl alcohol, ethylene/vinyl acetate copolymer, animal glue, and polyvinyl acetate, among others. However, a constant effort is being made by tissue manufacturers to fine new and better creping adhesives.